1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing an image display device, particularly, an image display device comprising a display panel formed by sealing a faceplate constituting the display surface of the display panel, and a rear plate arranged opposite to the faceplate with a space therebetween and constituting the back of the display panel.
2. Description of the Related Art
Conventional known electron emitting devices are roughly divided into two types including a thermoelectron emitting device and a cold-cathode electron emitting device. The cold-cathode electron emitting device includes a field emission type (referred to as a “FE type” hereinafter), a metal/insulating layer/metal type (referred to as a “MIM type” hereinafter), and surface conduction type electron emitting devices.
Known examples of the FE type are disclosed in W. P. Dyke & W. W. Dolan, “Field Emission”, Advance in Electron Physics, 8, 89 (1956), C. A. Spindt, “PHYSICAL Properties of thin-film field emission cathodes with molybdenum cones”, J. Appl., 47, 5248 (1976), etc.
Known examples of the MIM type are disclosed in C. A. Mead, “Operation of Tunnel-Emission Devices”, J. Appl. Phys., 32, 646 (1961), etc.
Examples of the surface conduction type electron emitting device are disclosed in M. I. Elinson, Radio Eng. Electron Phys., 10, 1290 (1965), etc.
The surface conduction type electron emitting device utilizes the phenomenon that an electric current is passed through a small-area thin film formed on a substrate in parallel with the film plane to emit electrons. As the surface conduction type electron emitting device, a device using a SnO2 thin film disclosed by Elinson, a device using an Au thin film [G. Dittmer, “Thin Solid Films”, 9, 317 (1972), a device using a In2O3/SnO2 thin film [M. Hartwell and C. G. Fonstad, “IEEE Thrns. ED Cong.”, 519 (1975), a device using a carbon thin film [Hisashi Araki, et al., Vacuum, Vol. 26, No. 1, p. 22 (1983)], etc.
In manufacturing an image display device using the above-described electron emitting device, an electron source substrate (rear plate) comprising the electron emitting devices arranged in a matrix thereon, and a fluorescent plate (faceplate) comprising a fluorescent material which emits light by excitation of an electron beam are prepared. The faceplate and the rear plate are arranged opposite to each other so that the electron emitting devices and the fluorescent material are located on the inside, with a package for providing a vacuum sealed structure and a spacer for providing an atmospheric pressure resistant structure being arranged therebetween. Then, the inside is sealed with a low-melting-point material used as a sealing material, such as frit glass or the like, and evaluated through a vacuum exhaust tube previously provided, and then the vacuum exhaust tube is sealed to form a display panel.
The above-described conventional manufacturing method requires a long time for manufacturing a display panel, and is not suitable for manufacturing a display panel in which, for example, the internal pressure is 10−6 Pa or less.
The problems of the conventional method are resolved by the method disclosed in, for example, Japanese Patent Laid-Open No. 11-135018.
The method disclosed in Japanese Patent Laid-Open No. 11-135018 comprises only the steps of aligning the faceplate and the rear plate in a single vacuum chamber, and then sealing the two substrates. Therefore, each of the other steps required for forming the display panel, i.e., the baking step, the gettering step, the electron beam cleaning step, etc., must be performed in a single vacuum chamber. Therefore, the time required for the manufacturing process is increased, thereby causing demand for significantly shortening the time of the manufacturing process.